Apparently playing high-action video games can lead to improvement in your vision. Apparently they found students who played little or no video games (this would be the part of the research that I would question) and gave them a visual test.

The researchers found a group of students who played little or no video games — which was a challenge in itself — and gave them a test that measured how well they could discern the orientation of a letter “T” within a crowd of other, distracting symbols.

Then the students were told to play games (the things that need to be done in the name of science). Different styles of games were used for each group. Tetris for one group and Unreal Tournament for the other. Apparently the Unreal players did better on the “T” test than the Tetris players did.
The debate appears to be not whether or not it is correct, but rather what part of your vision is actually improved.

The T test measures visual acuity, or the clarity of a person’s vision, according to the researchers, who are Daphne Bavelier, a professor of brain and cognitive sciences, and graduate student Shawn Green.

“The test they’re using is not for visual acuity,” she said after being told of the research. “They’ve trained their students to make rapid eye movements and to scan large areas to find objects of interest. … That is visual search.”

On a side note, Mrs Woodhouse does not seem to think that the improvements are worth the “risks”.

She also said playing video games “gives you brain damage,” although that seemed to be her subjective view rather than a scientific one.